1. Field of the Invention
The invention relates to an antenna module, more particularly to a concealed multi-frequency antenna module.
2. Description of the Related Art
Conventional external-type helical antenna and concealed-type planar inverted F (PIFA) antenna are generally applied to a variety of electronic apparatuses, such as mobile telephones. In actual applications, the conventional helical antenna is mounted externally on an electronic apparatus such that it is susceptible to damage. When the conventional PIFA antenna is applied to a mobile telephone with a reduced size, bandwidth requirements for a high frequency band, such as 1800 MHz and 1900 MHz, are not satisfied. Furthermore, the harmonics generated in a low frequency band, such as 900 MHz, interfere with signal transmission in a high frequency band, such as 1800 MHz.